If you’ve downloaded a file and are not sure you can trust it before opening it, did you know you can use Microsoft Security Essentials (MSE) to scan it for viruses without running a full virus scan? MSE lets you do this and it can help give you peace of mind before opening an unknown file.

This feature can be particularly useful if you’re opening a file from removable media (CD, DVD, external HDD etc.) and MSE’s real-time virus checker has not had a chance to do a preliminary scan at the file yet. If you’ve turned off real-time virus scanning, this will also help you avoid virus infection.

Caution: Even if a virus checker doesn’t detect a virus, never open a file from an untrusted source.

Realizing I didn’t have an infected file to use for this guide, I went to the source of many viruses: a torrent tracker and grabbed a copy of “Adobe Photoshop Lightroom v3.2″ (don’t worry, I promptly deleted it.)